The apparatus used for sanding, polishing, grinding, or other floor treatment operations contain a drive mechanism, which, for example, could be an electric or a hydraulic motor. This drive mechanism causes a floor treatment disc to rotate or vibrate on the surface of the floor while the apparatus is guided across the surface to be treated either manually or as part of a ride-on vehicle.
Because of the force needed to operate the drive mechanism, a disadvantage of conventional floor treatment devices is that the force includes a strong sideward component during the operation, making controlled floor treatment possible by the operator's use of a sufficient counter force. Otherwise, the machine tends to pull to one side. In addition, there also is the resulting disadvantage that, because of dynamic forces, the perimeter of the floor treatment disc always tries to penetrate into the floor or surface, thereby representing a severe impediment when treating a softer floor surface, like wood or cork floors. A conventional floor treatment device, when placed in operation, will tend to wander from the starting position unless the operator remains vigilant and maintains control of the apparatus with sufficient counter-force.
There exists a number of U.S. patents directed to drive heads for grinding, polishing, and similar operations including U.S. Pat. No. 862,747 issued to Miller on Aug. 6, 1907. Miller teaches a drive head with a stationary central gear that is concentric with a head that is directly connected to a drive motor. Planetary gears, meshing with the central gear revolve about the center axis of the head as it rotates. Therefore, according to the disclosed configuration, the planetary gears rotate in the same direction as the head. Discs having the abrasive material are attached to the planetary gears and thus also rotate in the same direction as the head. This causes a sideways force on the machine and a noticeable pattern in the treated floor.
U.S. Pat. No. 6,752,707 issued to Palushi on Jun. 22, 2004 teaches a power sanding machine with three circumferentially spaced cogged belts to drive three discs that are rotatably mounted on an inner bowl. The inner bowl is rotatably mounted to a housing, which, in turn, is connected to an operating handle. The belts drive the discs in a direction opposite to the direction of the inner bowl. However, belts tend to be too weak to drive the discs at a rate high enough for grinding operations.
U.S. Pat. No. 5,863,241 issued to Rottschy on Jan. 26, 1999 teaches a floor sanding or polishing device including a housing that can be guided across a floor. The housing carries a motor which rotates a plate in a first direction about a vertical axis. The plate carries a plurality of sanding or polishing discs that are rotatable in the same second directions which are opposite to the first direction of rotation of the plate. The discs are displaceable radially relative to the plate by centrifugal force to bring a gear of the disc into engagement with a ring gear affixed to the housing, whereby the discs are rotated about their respective axes in response to rotation of the plate. Such outer ring gear drives, however, are vulnerable to damage.
A robust planetary drive head that can perform in polishing, grinding, and cleaning applications with reduced transverse forces is therefore desired.